The present invention relates to organopolysiloxane emulsions and to a method for their preparation. In a particular aspect the present invention relates to nonionic organopolysiloxane emulsions which are useful as, for example, fiber-treatment agents, lubricants, release agents, glass fiber-treatment agents, lustrants, defoamers, and paint components.
Organopolysiloxane emulsions known in the art consist of the anionic and cationic organopolysiloxane emulsions obtained by the emulsion polymerization of organopolysiloxane in the presence of a strong acid or strong alkali {Japanese Patent Publication Number 34-2041 (2.041/59)}; the anionic and cationic organopolysiloxane emulsions prepared by the thermal emulsion polymerization of organopolysiloxane emulsified in water using benzenesulfonic acid or alkylbenzenesulfonic acid {Japanese Patent Publication Number 41-13995 (13,995/66)}; and the mechanically emulsified nonionic emulsions which are prepared by emulsifying relatively low-viscosity organopolysiloxane in the presence of a nonionic emulsifier using, for example, a colloid mill, line mill, or homomixer.
However, the aforesaid emulsion-polymerized emulsions suffer from a critical problem. Due to the use of anionic or cationic emulsifying agents and polymerization catalysts, the emulsion's stability is substantially impaired when an additive having the opposite ionicity is added during the course of the emulsion's utilization.
Another problem encountered in the aforesaid emulsion polymerization methods is that 5 to 15% oligomer is always produced due to the use of an equilibration reaction mediated by the polymerization catalyst. This oligomer is volatile, and when an emulsion obtained by such a method is used as one of various types of treatment agents, one finds that oligomer adheres on, for example, exhaust fans used in drying the treated material, with the resulting occurrence of an oily contaminant.
Furthermore, this oily debris can drop onto the treated substrate, causing stains.
In addition, the diorganopolysiloxanes prepared by prior emulsion polymerization methods have viscosities at most of 800,000 to 1,000,000 centistokes, and diorganopolysiloxanes having larger viscosities and diorganopolysiloxane gums cannot be prepared.
A further problem is the poor productivity resulting from the large energy consumption engendered by the requirement for heating during emulsion polymerization.
Furthermore in mechanical emulsification, the viscosity of the organopolysiloxane must be low enough to allow passage through the emulsifying device, and as a consequence it becomes quite difficult to obtain nonionic emulsions of high-viscosity organopolysiloxanes. The problem then arises that such mechanical emulsions cannot be used in applications such as fiber-treatment agents lubricants, release agents, glass fiber-treatment agents, lustrants, defoamers, and paint components where high-viscosity organopolysiloxanes are required.